         lat2 (:lat b)
         lon1 (:long a)
         lon2 (:long b)
-        R 6372.8
+        R 6372800
         dlat (Math/toRadians (- lat2 lat1))
         dlon (Math/toRadians (- lon2 lon1))
         lat1 (Math/toRadians lat1)

        a (+ (* (Math/sin (/ dlat 2)) (Math/sin (/ dlat 2)))
             (* (Math/sin (/ dlon 2)) (Math/sin (/ dlon 2))
                (Math/cos lat1) (Math/cos lat2)))]
    (* 1000 (* R 2 (Math/asin (Math/sqrt a))))))

(def coordinates (reverse (decode-polyline (polyline))))


(def pairs (partition 2 1 coordinates))

(def segments (map (fn [[a b]] (haversine a b)) pairs))

(def back-segment (take-segments segments meters-away))

